http://www.journalofclinicalvirology.com/article/S1386-6532(15)00130-4/abstract •HERVs gene expression levels were higher in kidney transplant recipients than in healthy subjects. •HERV-K and –W gene expression was significantly higher in transplant recipients with high CMV viral load. •CMV may facilitate in vivo HERV activation. •HERVs may be a potent diagnostic biomarker. Abstract Background Human endogenous retrovirus (HERVs) constitute approximately 8% of the human genome. Induction of HERV transcription is possible under certain circumstances, and may have a possible role in some pathological conditions. Objectives The aim of this study was to evaluate HERV-K and –W pol gene expression in kidney transplant recipients and to investigate the possible relationship between HERVs gene expression and CMV infection in these patients. Study design Thirty-three samples of kidney transplant patients and twenty healthy blood donors were used to analyze, HERV-K and –W pol gene RNA expression by relative quantitative relative Real-Time PCR. Result We demonstrated that HERVs pol gene expression levels were higher in kidney transplant recipients than in healthy subjects. Moreover, HERV-K and –W pol gene expression was significantly higher in the group of kidney transplant recipients with high CMV viral load than in the groups with no or moderate CMV viral load. Conclusion Our data suggest that CMV may facilitate in vivo HERV activation.